With the improvement of the living standard, there are more requirements for the vehicles. Presently, some vehicles are provided with head-up displaying systems. The head-up displaying system is disposed on a dashboard of the vehicle, projects information onto a front windshield in a form of text and image using the optical reflection principle. And a height of the projection image and that of eyes of a driver are generally at the same level. The driver may view a virtual image reflected by the front windshield with the projection image projected by the head-up displaying system. In this way, it is easy for the driver to combine a scene outside and the information displayed by the head-up displaying system during driving. The driver may view navigation information, the speed of the vehicle and other information without bowing his/her head, such that the problem of distracting the attention from the road ahead may be avoided, thus improving the driving security.
In the related art, the projection image of the head-up displaying system is limited to a certain position. However, the height differs from people to people. There is a requirement for adjusting the height of the projection image.